my car is being really weird... i just replaced the water pump, and my car makes a gurgling noise between 1 and 2k rpms, im assuming its coolant related? its coming from inside the head... the car drives fine... also, when my car is "warmed" up, it will go back down to cold when i turn the heat on.... in fact, i drove two hours this weekend and it was on cold the entire time

 

but when i turn the air to cold, it'll warm back up.... sometimes though it will warm up with the heat on, its sort of random...
and my fan doesnt come on?
coolant temp. sensor? thermostat?

 

anybody?! please

 

Kind of sounds like the thermostat since you say it warms up then cools back down. It's a cheap part, and if it's never been replaced, start there.

Has the coolant ever been flushed out?

Only other thing I can think of is to make sure you have bled the system of all the air. Leave the radiator cap open and run the car to normal operating temp, make sure the heat it on so the heater core opens up. It should bubble and all the air will escape.

edit: another reason I mention the thermostat, is right after I replaced my timing belt/water pump, the thermostat started sticking closed.